The present invention relates to driving a shaft which is journalled and mounted in pendulum bearings, and more particularly the invention relates to a system which includes one or more drive motors or engines, a transmission and reducing gear with slow rotational output and driving a pendulum-mounted shaft at a low rate. The particular field and in which the problem solved by the invention arose, is the driving of suction dredge cutting heads, whereby such a head is secured to the end of such a pendulum mounted shaft while the other end connects to a driving train.
Drives for underwater cutting and drilling have been constructed in the past in drum configuration with thrust bearings to relieve the drive from axial thrust as exerted upon the cutter. In other words, the output axle of the gear was concentrically surrounded by one or multiple steps type speed reducers. The gear is particularly supported by a boom which is part of the dredge.
A particular coupling with cambered teeth is connected here between the thrust bearing and the gear. The thrust bearing takes up the axial forces acting on drive shaft, and the particular coupling compensates for any angular deflection between the axis of the output shaft of the gear on the one hand and the pendulum mounted shaft on the other hand and as may occur because the head shaft is usually additionally supported by highly elastic rubber bearings acting on the shaft close to the head.
The arrangements outlined above are satisfactory for engines or motors with large torques and small rotational speeds, and are particularly quite economical. This is particularly so as the reduction ratios are small and the gears have small diameters in these instances, (see for example, H. M. Hiersig in VDI-Zeitschrift 1965, Vo 6, pages 270 to 274 -- Hydraulic drive of suction dredge cutting heads). The situation is quite different, if large torques are produced by many small, fast running drive motors. Plural reducing stages are needed here and the several drive channels have to be combined for obtaining a single rotary output. Consequently, some of the gears needed here will be quite large, and can be placed in and mounted to a dredge boom with great difficulties only.